Abstract: The effect of micro-arc discharge of the Ti anode on the decolorization of methyl orange was studied. It was found that the decolorization of methyl orange was prominent. Under the conditions of peak-value voltage 550 V, pulse frequency 300 Hz, duty circle of positive pulse 1/180, anode area 25 mm~50 mm, and react ion time 60 min in H3PO4 electrolyte (0.3 mol/L), the decolorization of methyl orange (600 ml, 20 mg/L) was 94%. During the discharge, the ceramic layer formed on the Ti anode was anatase and the wavelength of micro-arc was between 300 and 350 nm, which were proved by XRD and spectrum analysis. It was hinted that there might be photocatalysis, electrocatalysis, wave-like sono-catalysis during micro-arc discharge. The contrastable experiments showed that the individual effect of such catalysis was inapparent. The react ion mechanism was thought that the dominating process was plasma catalysis with the harmonious effects of multiple energy fields on the Ti anode during micro-arc discharge in the degradation of organic compounds.

Key words: micro-arc discharge, titania, plasma catalysis, multiple energy field, harmonious catalysis, methyl orange, decolorization;